PROVIDENCE, R.I. ? A grand jury opened an investigation Wednesday into the nightclub inferno that killed 97 people, and members of the heavy metal group whose pyrotechnics are suspected of starting the fire could testify as early as today.

At least two members of the band Great White were seen entering the National Guard training center in East Greenwich where the grand jury met behind closed doors.

However, no one testified, and most of the session was devoted to preliminary talks between prosecutors and lawyers for the band, according to two sources close to the case who spoke on condition of anonymity.

In nearby Pawtucket, more than 200 grief-stricken friends and relatives said goodbye to victim Dennis Smith, 36, who had gone to the concert at The Station because a friend had an extra ticket.

About 1,000 people — many of them teenagers — packed St. Jude’s Church in Lincoln for a memorial service for 18-year-old Nicholas O’Neill of Pawtucket, the lead singer of a band he and his brothers formed. In West Warwick, about 500 people attended a private Mass for another victim of the blaze, 38-year-old Carlos Pimental.

Flames swept through the West Warwick club last Thursday after the band set off a pyrotechnic display during its first song. The band has said it received approval to use special effects, but the two brothers who own the club have denied giving permission.

Legal experts and fire investigators said the owners, Jeffrey and Michael Derderian, along with band members, could be indicted on such state charges as involuntary manslaughter or second-degree murder. Federal charges haven’t been ruled out.

The Derderians were in the process of selling the business when the fire broke out; just hours before, two men, Michael O’Connor and Daniel Gormley, filed papers with the state forming a company to run it. According to the town clerk, the Derderians were scheduled to come in the following day to begin transferring the liquor license.